Effectiveness of mRNA COVID-19 Vaccine Boosters Against Infection, Hospitalization, and Death: A Target Trial Emulation in the Omicron (B.1.1.529) Variant Era.

Abstract

BACKGROUND:

The effectiveness of a third mRNA COVID-19 vaccine dose (booster dose) against the Omicron (B.1.1.529) variant is uncertain, especially in older, high-risk populations.

OBJECTIVE:

To determine mRNA booster vaccine effectiveness (VE) against SARS-CoV-2 infection, hospitalization, and death in the Omicron era by booster type, primary vaccine type, time since primary vaccination, age, and comorbidity burden.

DESIGN:

Retrospective matched cohort study designed to emulate a target trial of booster vaccination versus no booster, conducted from 1 December 2021 to 31 March 2022.

SETTING:

U.S. Department of Veterans Affairs health care system.

PARTICIPANTS:

Persons who had received 2 mRNA COVID-19 vaccine doses at least 5 months earlier.

INTERVENTION:

Booster monovalent mRNA vaccination (Pfizer-BioNTech's BNT162b2 or Moderna's mRNA-1273) versus no booster.

MEASUREMENTS:

Booster VE.

RESULTS:

Each group included 490 838 well-matched persons, who were predominantly male (88%), had a mean age of 63.0 years (SD, 14.0), and were followed for up to 121 days (mean, 79.8 days). Booster VE more than 10 days after a booster dose was 42.3% (95% CI, 40.6% to 43.9%) against SARS-CoV-2 infection, 53.3% (CI, 48.1% to 58.0%) against SARS-CoV-2-related hospitalization, and 79.1% (CI, 71.2% to 84.9%) against SARS-CoV-2-related death. Booster VE was similar for different booster types (BNT162b2 or mRNA-1273), age groups, and primary vaccination regimens but was significantly higher with longer time since primary vaccination and higher comorbidity burden.

LIMITATION:

Predominantly male population.

CONCLUSION:

Booster mRNA vaccination was highly effective in preventing death and moderately effective in preventing infection and hospitalization for up to 4 months after administration in the Omicron era. Increased uptake of booster vaccination, which is currently suboptimal, should be pursued to limit the morbidity and mortality of SARS-CoV-2 infection, especially in persons with high comorbidity burden.

PRIMARY FUNDING SOURCE:

U.S. Department of Veterans Affairs.

• Authors: George N Ioannou, Amy S B Bohnert, Ann M O'Hare, Edward J Boyko, Matthew L Maciejewski, Valerie A Smith, C Barrett Bowling, Elizabeth Viglianti, Theodore J Iwashyna, Denise M Hynes, Kristin Berry, COVID-19 Observational Research Collaboratory (CORC)
• Journal: Annals of internal medicine (Ann Intern Med) Vol. 175 Issue 12 Pg. 1693-1706 (12 2022) ISSN: 1539-3704 [Electronic] United States
• PMID: 36215715 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• 2019-nCoV Vaccine mRNA-1273
• BNT162 Vaccine
• COVID-19 Vaccines

Topics

• United States
• Humans
• Male
• Aged
• Middle Aged
• Female
• 2019-nCoV Vaccine mRNA-1273
• BNT162 Vaccine
• COVID-19
• COVID-19 Vaccines
• Cohort Studies
• Retrospective Studies
• SARS-CoV-2
• Hospitalization